There are conventionally used foamed materials when optical members such as image display members fixed on image display apparatuses such as liquid crystal displays, electroluminescence displays and plasma displays, display members installed on so-called “cellular phones,” “smartphones” and “personal digital assistants,” cameras and lenses are fixed on predetermined sites (for example, housings). As such foamed materials, there have been used compression-molded high-density fine-cell urethanic foamed bodies having a closed cell structure and low-density urethane and besides, polyethylenic foamed bodies having closed cells and an expansion ratio of about 30, and the like. Specifically, there are used, for example, a gasket (see Patent Literature 1) composed of a polyurethanic foamed body having an apparent density of 0.3 to 0.5 g/cm3, and a sealing material for electric or electronic devices (see Patent Literature 2) composed of a foamed structural body having an average cell diameter of 1 to 500 μm.
In recent years, however, along with more and more thickness reduction of products installed with optical members (image display apparatuses, cameras, lenses and the like), the clearance of portions where foamed materials are used is likely to be remarkably reduced. Along with the clearance reduction, the thickness of the foamed members needs to be made small, but conventional foamed materials, when being made small in thickness, does not exhibit sufficient impact absorption. Hence, for example, in the case where electric or electronic devices with a display member, such as “smartphones,” are dropped on the ground or the like, foamed sheets are demanded which absorb impacts on collision, and prevent breakage of the display members.
Further along with the function enhancement of electronic devices such as PCs (personal computers), tablet PCs, PDAs (personal digital assistants) and cellular phones, on impact absorption sheets to be used for the breakage prevention of display members and the like, other members (for example, a thermoconductive layer) are laminated and incorporated. Along with the further thickness reduction of the electronic devices in recent years, there has been demanded further thickness reduction of members such as impact absorption sheets to be used therefor, and there has been demanded the thickness reduction or the elimination of a pressure-sensitive adhesive or adhesive layer in lamination of the impact absorption sheet with another member.